• Southern Ontario Hiking Resources


Why use Deet?

Deet is recommended because it works. One study in Alaska revealed that DEET on the skin reduced the number of mosquito bites from a maximum of 3360 bites per hour to just 1 per hour!


Why is it so highly recommended?

Deet-productsIn the summer of 2002, a study in The Journal of The American Medical Association compared DEET to other repellents. Deet widely outperformed them all.
DEET protected for about five hours
Soybean oil relents worked for only about two hours
Citronella was completely ineffective and may even have attracted mosquitoes
Eucalyptus oil-based repellents are under study but seem promising.

The July 2005 issue of Consumer Reports finds that repellents containing 7 percent picardin are as effective as 10 percent deet. One product now on the marketplace is called Cutter Advanced. If you don’t like deet’s smell or feel on the skin, you might want to try products with 7 percent picardin to see how they work for you.



Why is it called DEET?

Back to high school chemistry. The chemical name is N, N diethyl-m-toluamide, today often called N, N diethyl-3-methylbenzamide. The “diethyl” means two ethyl groups (C2H5) and thus the double “E” in DEET.


Are there problems using Deet?

It can wreck your sunglasses and the crystal of your watch making them both cloudy as it dissolves part of the plastic. It is a potent plasticizers. So what does it do to my skin?
It does move easily though the skin and irritates mucous membranes like your eyes and lips. There have been some cases reported of serious reactions to DEET. Still these reactions add up to fewer than 50 cases over the 40 years DEET has been in widespread use.


How strong should DEET be?

Adults should not use anything over a 30% solution. Raising the concentrations higher makes little difference in the protection. Children should be using 10% DEET solutions.


How does Deet work?insects0669

DEET works by corrupting receptors on the mosquito’s antennae. A blood seeking mosquito hones in on you by detecting three things: 1) your body heat, 2) the carbon dioxide you exhale, and 3) a variety of chemicals your body excretes on your skin, the most important of which is lactic acid. Some receptors on a female mosquito’s antennae are tuned to this lactic acid and nothing else. DEET turns off those receptors, so the nerves connected to them simply don’t fire. The shutdown of the lactic acid receptors by DEET blinds the female mosquito to our presence regardless of the carbon dioxide and the moist heat from our body.


How do mosquitoes react to deet?

When the female mosquito flies into areas where lactic acid is detected, she goes immediately into active hunting mode. When DEET is in the air, she flies erratically apparently searching for some scent of a target, unaware that one is nearby.


Can I change my skin secretions?

Don't eat bananas, peanuts or peanut butter, or chocolate before going into the woods. You might even consider giving these up for the summer months. They cause your body to secrete scents that attract mosquitoes. The chemical serotonin is found in these products and mosquitoes hone in on those scents. Citrus products and taking vitamin B1 (100 mg daily) tend to repel mosquitoes. Some reports indicate taking daily doses of odourless garlic capsules help in repelling mosquitoes but I have doubts about that idea.


How can I avoid mosquitoes?

Mosquitoes are most active at dawn and dusk, so stay out of the woods at those times. Mosquitoes don't fly when it's windy, so you can hike when there is a good breeze. Avoid hiking in wetland areas in mosquito season.


Important Precautions When Using Deet

  • Apply repellents only to exposed skin and/or clothing (as directed on the product label). Do not use repellents under clothing.
  • Never use repellents over cuts, wounds or irritated skin.
  • Do not apply to eyes or mouth, and apply sparingly around ears. When using sprays, do not spray directly on face — spray on hands first and then apply to face.
  • Do not allow children to handle the product. When using on children, apply to your own hands first and then put it on the child. Do not apply to children's hands.
  • Use just enough repellent to cover exposed skin and/or clothing. Heavy application and saturation generally are unnecessary for effectiveness.
  • After returning indoors, wash treated skin with soap and water or bathe. This is particularly important when repellents are used repeatedly in a day or on consecutive days. Also, wash treated clothing before wearing it again. (This precaution may vary with different repellents — check the product label.)
  • If a child develops a rash or other apparent allergic reaction from an insect repellent, stop using the repellent, wash it off with mild soap and water and call a local poison control center for further guidance.


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